Spirits are distiller not brewed. The brew for whiskey say is probably something like 5 to 10% I would imagine.
When I was told about TNP this AM I said – are they addins spirit as most beer yeasts I know of die off at around 8%ish.
What Brew Dog have done is brew a stout to about 5.5%, matured it for 15 months in whiskey casks and then (the clever bit) frozen the beer in the local ice cream factory. This freezes a large proportion of the water, the ever strengthening brew is then tapped off to a fresh vessel and refrozen. Eventually they got to 32%. so while they haven't "added" a spirit or "distlled" their brew they have removed water to increae the ABV.
My understanding is that this was one of the ways that vodka/schnapps type drinks came about. Wines or beers left out in the snow in northern countries or mountains, would part freeze. The locals drank the liquid part and found it was much stronger tasting and got them smashed quicker than the wine did in the summer months
thus endeth the lecture.